Commercial building

Opera Block House (Goodhue County, Minnesota)
Opera Hall Block (Gentry County, Missouri)
Opera House (Webster County, Nebraska)
Opera House and Yates Bookshop Building (Fayette County, Kentucky)
Opera House Block/Central Block Building (Larimer County, Colorado)
Opera House-Starnes Jewelers Building (Stanly County, North Carolina)
Optima Grain Elevator (Texas County, Oklahoma)
Oregon & Washington Territory Investment & Trust Company (Multnomah County, Oregon)
2 story Cast Iron & Masonry Bank building built 1876
Oregon Bank Building (Klamath County, Oregon)
Oregon Portland Cement Building (Multnomah County, Oregon)
Oregon State Bank Building (Multnomah County, Oregon)
Oriental Building Association No. 6 Building (Washington, District of Columbia)
Orme Wilson and Company Storehouse (Loudon County, Tennessee)
Oroville Commercial District (old) (Butte County, California)
Osage Bank of Fairfax (Osage County, Oklahoma)
Oscar Easley Block (Orange County, California)
Oscar Redman Building (Searcy County, Arkansas)
Osceola Times Building (Mississippi County, Arkansas)
Osler Building (Oklahoma County, Oklahoma)
Osterman and Tremaine Building (Dodge County, Nebraska)
Osterman's Shell Station (Mohave County, Arizona)
Otero's 66 Service (Valencia County, New Mexico)
Otis Elevator Company Building (Multnomah County, Oregon)
Ott's Assay Office (Nevada County, California)
Otto Schlemmer Building (Montgomery County, Indiana)
Our House (Gallia County, Ohio)
Overfield Tavern (Miami County, Ohio)
Overland Arizona Co. (Maricopa County, Arizona)
Overton Hygienic Building (Cook County, Illinois)
Ovide LaCour Store (Pointe Coupee Parish, Louisiana)
Owl Blacksmith Shop (Custer County, Oklahoma)
Owl Drug Store (Beckham County, Oklahoma)
Owl Night Lunch Wagon (Wayne County, Michigan)
The precursor of today's diner.
P. J. Barrett Block (Berkshire County, Massachusetts)
P.A. Sanning Store (Miller County, Missouri)
Pacific Brewing and Malting Company (Pierce County, Washington)
Pacific Building (Multnomah County, Oregon)
Pacific Desk Building (Bernalillo County, New Mexico)
Pacific Electric Railway Company Substation No. 8 (Los Angeles County, California)
Pacific Express Stable (Denver County, Colorado)
Pacific National Bank Building (Pierce County, Washington)
Lost six-story steel-framed skyscraper
Pacific Press Building (Alameda County, California)
Pacific Telephone and Telegraph Building (Cowlitz County, Washington)
Packard Service Building (Multnomah County, Oregon)
Packer's National Bank Building (Douglas County, Nebraska)
Pacolet Mill Office (Spartanburg County, South Carolina)
Historic Textile Mill office building in Pacolet, SC
Paddock Arcade (Jefferson County, New York)
Paddock Building (Franklin County, New York)
Paden's Drug Store (Lincoln County, New Mexico)
Page Brothers Building (Cook County, Illinois)
Page Coal and Coke Company Store (McDowell County, West Virginia)
Pahaska Tepee (Park County, Wyoming)
Paige Motor Car Co. Building (San Francisco County, California)
Paine Bank (Berrien County, Michigan)
Paine Furniture Building (Suffolk County, Massachusetts)
Palace Clothing Company Building (Jackson County, Missouri)
Palace Diner (York County, Maine)
One of two diners still in existence built by the Pollard Company of Lowell, MA
Palace Drug Store (Creek County, Oklahoma)
Palais Royale Building (St. Joseph County, Indiana)
Palm Beach Mercantile Company (Palm Beach County, Florida)
Palmetto Building (Richland County, South Carolina)
Palmolive Building (Cook County, Illinois)
Pan American Union (Washington, District of Columbia)
Panhorst Feed Store (Franklin County, Missouri)
Parham Apothecary Building (Jefferson County, Alabama)
Paris Lumber Company Building (Bear Lake County, Idaho)
Paris Photo Studio (Bear Lake County, Idaho)
Park Building (Worcester County, Massachusetts)
Park Building (Cuyahoga County, Ohio)
Park Row Building (New York County, New York)
Parker and Weeter Block (Carbon County, Utah)
Parker Building (Crow Wing County, Minnesota)
Parker Lumber Company Complex (Brazos County, Texas)
Parker's Store (Hillsborough County, New Hampshire)
Parkesburg National Bank (Chester County, Pennsylvania)
Parkhurst Building (Los Angeles County, California)
Parkinson & Co. Building (Okmulgee County, Oklahoma)
Parks In The Pines General Store (Coconino County, Arizona)
Parkview Apartments (Multnomah County, Oregon)
Parmley Land Office (Edmunds County, South Dakota)
Parrott Insurance Building (Clarke County, Georgia)
Parson and Scoville Building (Vanderburgh County, Indiana)
Pascal Building (Iberia Parish, Louisiana)
Paso Robles Almond Growers Association Warehouse (San Luis Obispo County, California)
Pat's Lounge (Cibola County, New Mexico)
Pataskala Banking Company (Licking County, Ohio)
Patroon Agent's House and Office (Rensselaer County, New York)
Patterson Law Office (Merrick County, Nebraska)
Patton and Loomis Block (Hampden County, Massachusetts)
Patton Block Building (Warren County, Illinois)
Patton Building (Hampden County, Massachusetts)
Paul Brown Building (St. Louis, Missouri)
Paul Building (Harris County, Texas)
Paula's Slow Down Diner (Hall County, Texas)
Pawtucket Elks Lodge Building (Providence County, Rhode Island)
Pawtucket Times Building (Providence County, Rhode Island)
Pay'n Takit #13 (Maricopa County, Arizona)
Pay'n Takit #25 (Maricopa County, Arizona)
Pay'n Takit #5 (Maricopa County, Arizona)
Payne Avenue State Bank (Ramsey County, Minnesota)
Peabody Museum of Salem (Essex County, Massachusetts)
Pearce General Store (Cochise County, Arizona)
Peck Memorial Library (Cortland County, New York)
Peck Tavern (New London County, Connecticut)
Peerless Coal Company Store (McDowell County, West Virginia)
Peerless Motor Company (Douglas County, Nebraska)
Peerless Rooms Building (Jackson County, Oregon)
Peerless Saloon (Calhoun County, Alabama)
Peggy Ann Building (Mahoning County, Ohio)
Pekin Noodle Parlor (Silver Bow County, Montana)
Pence Automobile Company Building (Hennepin County, Minnesota)
Pender's Store (Jackson County, Florida)
Pendergrass Building (Macon County, North Carolina)
Pendleton House (Pendleton County, Kentucky)
Pendrey Drug Store Building (Bear Lake County, Idaho)
Penn's Park General Store Complex (Bucks County, Pennsylvania)
Penn's Store (Boyle County, Kentucky)
Penrose Wolf Building (Somerset County, Pennsylvania)
People's Bank (Hancock County, West Virginia)
People's Bank of Friendsville (Blount County, Tennessee)
People's Co-op Building (Utah County, Utah)
People's General Store (San Bernardino County, California)
People's National Bank (Iberia Parish, Louisiana)
People's National Bank Building (Smith County, Texas)
People's Savings Bank (Linn County, Iowa)
A Louis Sullivan "Jewel Box" bank, severely damaged in the Flood of 2008, undergoing renovation
People's Supply Company (Baldwin County, Alabama)
Peoples Bank and Loan Building (Lafayette County, Arkansas)
Peoples Bank and Trust Company (Lee County, Mississippi)
Peoples Bank Company Building (Franklin County, Ohio)
Peoples Bank of Biloxi (Harrison County, Mississippi)
Peoples Building & Loan Building (Pulaski County, Arkansas)
Peoples Gas Building (Cook County, Illinois)
Peoples National Bank Building--Fries Building (Rock Island County, Illinois)
Percy--Lobdell Building (Lafourche Parish, Louisiana)
Pergola Pioneer Building and Totem Pole (King County, Washington)
Perkins Building (Pierce County, Washington)
Perkins Opera House (Jefferson County, Florida)
Perkins Store (Gila County, Arizona)
Perring Building (Dickinson County, Kansas)
Perry Wiles Grocery Company (Muskingum County, Ohio)
Perry-Payne Building (Cuyahoga County, Ohio)
Perryville Tavern (Hunterdon County, New Jersey)
Persy's Place (Providence County, Rhode Island)
Pet Plaza (St. Louis, Missouri)
Pete's Crossing Diner (Hennepin County, Minnesota)
Pete's Hamburgers (Crawford County, Wisconsin)
The "Best Hamburgers in the World" are made in Prairie du Chien!
Peter Joplin Commercial Block (Garland County, Arkansas)
Peter Kirk Building (King County, Washington)
Peter Pierce Store (Plymouth County, Massachusetts)
Peterboro Land Office (Madison County, New York)
Peters Cartridge Company (Warren County, Ohio)
Peters Paper Company Warehouse (Denver County, Colorado)
Peters Shoe Company Building (St. Louis, Missouri)
Peters' Barber Shop (Scott County, Iowa)
Petroleum Building (Tulsa County, Oklahoma)
Pettit Cleaners Building (Cowley County, Kansas)
Pevely Dairy Company Buildings (St. Louis, Missouri)
Peyton Building and Peyton Annex (Spokane County, Washington)
Peyton-Ellington Building (Charlottesville, Virginia)
Pfeifer Brothers Department Store (Pulaski County, Arkansas)
Phelps Dodge General Office Building (Cochise County, Arizona)
Phelps, Arah, Inn (Litchfield County, Connecticut)
Philadelphia Contributionship (Philadelphia County, Pennsylvania)
Philadelphia Savings Fund Society Building (Philadelphia County, Pennsylvania)
Philadelphia Stock Exchange (Philadelphia County, Pennsylvania)
Philadelphia Watch Case Company Building (Burlington County, New Jersey)
Philadelphia Wholesales Drug Company Building (Philadelphia County, Pennsylvania)
Philcade Building (Tulsa County, Oklahoma)
Philip Carey Building (Mecklenburg County, North Carolina)
Philip Dougherty Tavern (Chester County, Pennsylvania)
Philips-Thompson Buildings (New Castle County, Delaware)
Philipsburgh Building (Westchester County, New York)
Phillip Hardware Store (Ellis County, Kansas)
Phillips 66 Station (Jackson County, Arkansas)
Phillips 66 Station #473 (Tulsa County, Oklahoma)
Phillips and Trosper Buildings (Lampasas County, Texas)
Phillips Block (Minnehaha County, South Dakota)
Phillipsburg General Store (Laclede County, Missouri)
Philtower (Tulsa County, Oklahoma)
Phipps--Wallace Store Building (St. Louis, Missouri)
Phipps-McElveen Building (Allegheny County, Pennsylvania)
Phlegar Building (Montgomery County, Virginia)
Phoenix Bank of Nansemond (Suffolk, Virginia)